1. Field
The present invention relates generally to a method and apparatus for manufacturing electro-optic devices and more particularly to a method and apparatus for manufacturing electro-optic devices that have multiple layers and which can be produced by laminating or otherwise integrating two or more discrete electro-optic units or modules.
2. Related art
Photovoltaic devices represent one of the major sources of environmentally clean and renewable energy. They are frequently used to convert optical energy into electrical energy. Typically, a photovoltaic device is made of one semiconducting material with p-doped and n-doped regions. The conversion efficiency of solar power into electricity of this device is limited to a maximum of about 37%, since photon energy in excess of the semiconductor's bandgap is wasted as heat. A photovoltaic device with multiple semiconductor layers of different bandgaps is more efficient: an optimized two-bandgap photovoltaic device has the maximum solar conversion efficiency of 50%, whereas a three-bandgap photovoltaic device has the maximum solar conversion efficiency of 56%. Realized efficiencies are typically less than theoretical values in all cases.
Multi-layered or multi junction devices are currently manufactured as monolithic wafers, where each semiconductor layer is crystal-grown on top of the previous one. As a result, the semiconductor layers are electrically connected in series and have to be current-matched, in order to obtain maximum conversion efficiency.